[danadam]

> even just a volume change by the listener if it's applied digitally in the 16 bit realm ...

I think that "if" is doing a heavy work here.

[hunter2_]

Maybe it's an uncommon scenario these days, but not too terribly long ago I think it was fairly typical for software audio players to be 16-bit and offer volume controls, and anything other than 100% would completely ruin most benefits of dither.